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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
bolt-clamped Langevin type vibrator, and more particularly to a vibrator with excellent
temperature characteristics. (Prior Art) Metal blocks are disposed on both end faces of an
annular electrostrictive vibration element consisting of a combination of a piezoelectric element
and a terminal plate, and these are inserted through the inside of the electrostrictive vibration
element. Bolted Langevin type vibrators in which both ends are integrated with a pair of metal
blocks by a central bolt made of gold If4 are known, and in fields intended for ultrasonic
application, machine tools or mixing 1 dispersion, including cleaning of various articles It is
widely used. (Problems to be Solved by the Invention) However, when cleaning the article by
immersing the vibrator in a high temperature liquid, a void is generated due to the difference in
thermal expansion between the metal block and the electrostrictive vibration element, and There
is a problem that the sound wave characteristics deteriorate. That is, an aluminum alloy is
generally used as a material of a pair of metal blocks and a central bolt in order to improve
vibration radiation. Although a selection of magnesium alloy, titanium alloy, nickel chrome steel
or more is selected and used, the center bolt and the pair of metal blocks may be selected from
materials having similar linear expansion coefficients or similar materials. Is easier to stretch due
to its elongated shape than the metal block, which loosens the connection between the metal
block and the electrostrictive vibration element, creates a gap, degrades the temperature
characteristics, and significantly reduces the ultrasonic characteristics, especially at high
temperatures. . An object of the present invention is to solve the above-mentioned problems and
to provide a vibrator having excellent temperature characteristics. (Means for Solving the
Problems) According to the present invention, an annular electrostrictive vibration element, a
pair of metal blocks having screw holes in the center in contact with both end surfaces of the
electrostrictive vibration element, and the annular electrostriction The present invention relates
to a high temperature bolted Langevin type vibrator composed of a ceramic center bolt which is
inserted through the inside of a vibrating element and screwed and fixed to a screw hole of each
metal block. In the present invention, annular electrostrictive vibration! ! The element is formed
by alternately laminating a piezoelectric element and a terminal plate, and the piezoelectric
element uses a known material such as lead zirconate titanate (PZT) or the like, and the terminal
plate uses a phosphor bronze plate or the like. The metal block is also selected from well-known
vibration radiative metals such as the aluminum alloy described above. The central bolt made of
ceramic is not particularly limited in its type K, but silicon carbide or silicon nitride is preferable
in terms of high temperature strength. (Operation) For example, when silicon carbide is used for
the central bolt and aluminum is used for the metal block, the #I expansion coefficient is
compressed by the metal block by a rise of two because silicon carbide is a fraction of aluminum.
There is no gap between the electrostrictive vibration element and the metal block. EXAMPLES
The present invention will now be described in detail. FIG. 1 is a cross-sectional view showing a
high temperature bolted Langevin anti-oscillator according to an embodiment of the present
invention. In the figure, 1 denotes an annular electrostrictive vibration element, and a PZT
sintered body of 30 mmφ × 1lanφ × 5 is polarized in the thickness direction to impart
electrostrictive properties, and a pair of piezoelectrics whose positive end faces face each other
inside With element 1a, la '. It consists of a phosphor bronze plate of
30.5armφX11mmφX0.2mmt, and the pressure 1! It is comprised from the terminal end 1b
inserted between elements and the terminal board 1c and lc 'distribute ¦ arranged to the negative
electrode side (outer side) end surface. 2 and 3 are in contact with both negative electrode side
end faces of the electrostrictive vibration element 1, and fl # tension coefficient (25 to 300 ° C.)
provided with screw holes 2a and 3a drilled in the center of the contact surface Is a metal block
of a high strength aluminum alloy of 30 mmφ x 42 rrml with 24 × 10-'/ "C, and 4 is a silicon
carbide sintered body having a coefficient of linear expansion (25-300C) of 4.2 × 10" 6 / ° C.
They are studs (center bolts) provided with male screws 4a and 4btj [MIOX effective screw
length attack 120-male threads 4a and 4btj] at both ends of the total length 50 + mn. The male
screw 4a was screwed into the screw hole 2alC of the metal block 2, and the screw hole 3a of the
metal block 3 was screwed together by a male torque 4bK 500 kg · country torque to form a
vibrator. The mechanical Q from normal temperature to 160 ° C. was measured for the
photographing moving element by an admittance measuring device set to an east condition of an
input voltage iov and a resonance frequency of 28 KHz. As a result, as shown in FIG. 2, the
average reduction rate of mechanical Q from normal temperature to 160 ° C. was only about 10
inches. In the above embodiment, electrostrictive vibration g! Although two annular piezoelectric
elements and three annular terminal plates are combined as elements, one piezoelectric element
may be used, and a large number of pressure T! A combination of an L element and a terminal
plate may be used. (Effects of the Invention) The vibrator of the present invention is excellent in
ultrasonic characteristics (mechanical Q) even at high temperatures, and is suitable for use as a
vibration source of an ultrasonic cleaner or the like.
Brief description of the drawings
FIG. 1 is a longitudinal sectional view of a high temperature bolted Langevin type vibrator
according to the present invention, and FIG. 2 is a graph showing the relationship between the
temperature of the vibrator of FIG. 1 and mechanical Q.
Explanation of symbols 1 ··· Electrostrictive vibration element 2 ··· Leather key $ metal block 3 ···
Section dark metal block 4 ··· Center bolt 4b1. Electric next shooting S 孕 East 2.3: f A ヮ O ヮ Z
仝: ホ し ホ 2 二 ('C) second figure